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Year : 2021  |  Volume : 9  |  Issue : 3  |  Page : 112-117

Strabismus surgery in poor binocular potential: Change in quality of life

1 Department of Ophthalmology, Military Hospital, Ahmedabad, Gujarat, India
2 Department of Ophthalmology, KGMU, Lucknow, Uttar Pradesh, India
3 Department of Ophthalmology, Armed Forces Medical College, Pune, Maharashtra, India

Date of Submission02-Nov-2019
Date of Decision19-May-2021
Date of Acceptance14-Jun-2021
Date of Web Publication27-Sep-2021

Correspondence Address:
Rolli Khurana
Department of Ophthalmology, Military Hospital, Ahmedabad - 380 004, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcor.jcor_88_19

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Background: Previous studies prove improvement in quality of life (QOL) after strabismus surgery. Aims: The aim is to study the change in QOL and binocular functions after strabismus surgery in patients with poor binocular potential. Setting and Design: A tertiary care center-based prospective study was done over a period of 1 year to evaluate the change in scores of adult strabismus-20 (AS-20) questionnaire after successful strabismus surgery. Materials and Methods: All patients above 10 years attending the orthoptic clinic with horizontal squint were evaluated for their probability of gaining binocularity on binocular potential score and were graded into four categories. Those with poor grade of binocular potential, having a poor chance of regaining binocularity after surgery, were included in the study. They underwent surgical ocular alignment and answered the AS-20 questionnaire for QOL preoperatively and 3 months postoperatively. Statistical Analysis Used: Comparison of preoperative scores was done using unpaired t-test. The mean pre- and post-operative scores were compared using paired t-test. Two-sided significance level with P < 0.05 was considered statistically significant. Results: Out of 53 patients, surgical outcomes of 5 were outside successful limits. Of the remaining, 18 (37.5%) were esotropic and 30 (62.5%) had exotropia. Improvement in the mean psychosocial and functional scores was 13.1 ± 6.0 and 7.6 ± 6.3, respectively. Mean overall, psychosocial, and functional QOL scores were significantly higher after successful surgical ocular alignment. Conclusion: Statistically significant improvement occurs in psychosocial and functional QOL of strabismus patients (on AS-20) with poor binocular potential undergoing successful strabismus surgery. Thus, ocular alignment in such cases can be a feasible option for improving QOL rather than mere cosmetic comeback.

Keywords: Adult strabismus questionnaire quality of life, poor binocular potential, strabismus

How to cite this article:
Khurana R, Agrawal S, Singh V, Agrawal M. Strabismus surgery in poor binocular potential: Change in quality of life. J Clin Ophthalmol Res 2021;9:112-7

How to cite this URL:
Khurana R, Agrawal S, Singh V, Agrawal M. Strabismus surgery in poor binocular potential: Change in quality of life. J Clin Ophthalmol Res [serial online] 2021 [cited 2023 Jun 8];9:112-7. Available from: https://www.jcor.in/text.asp?2021/9/3/112/326796

Meaningful change in quality of life (QOL) is determined by using an integrated method that combines information from anchor-based and distribution-based methods and adjusts for baseline severity and regression to the mean, thus reflecting the difference the procedure makes in the self-confidence and functionality of a person.[1] Adults with strabismus suffer from low self-esteem and have problems with interpersonal relationships and also deal with social anxiety.[2] They feel so conscious about their appearance that it hampers their social, economic, and personal growth, thus deteriorating their overall QOL. Patients with strabismus due to poor vision in one eye (amblyopes and sensory strabismus) or those having a large deviation over a prolonged period such that they have not enjoyed binocularity since childhood are usually the ones who have a meager chance of regaining binocular fusion postoperatively, that is, have poor binocular potential.[3] To quantify binocular potential, a scoring system, the binocular potential score (BPS), has been described. It grades the postoperative binocular potential into four categories (I – Best, IV – Weakest) [Annexure 1]. It evaluates seven components; each being given a score between 1 and 5. The last two components, which are responses on the Worth four-dot test (WFDT) and synoptophore, evaluate the sensory status of the patients. The change in cumulative score of these two components has been studied separately as change in binocular functions.

Patients with poor binocular potential are traditionally advised to undergo strabismus surgery for “cosmetic” improvement. In them, a “perfect” postoperative outcome is rarely attainable because sensory mechanisms required to maintain a stable ocular alignment are compromised. In them, an acceptable result would vary depending on the motor outcome and the patient's perception.[3] Strabismus affects not only the appearance but also social aspects such as job opportunities, conscious of their appearance to others, and inability to make friends. Hence, surgery for strabismus in these cases, especially with poor binocular potential, should not be considered as merely cosmetic as it also has a great impact on restoring normalcy to life. Measuring health-related QOL is an important adjunct to clinical examination as it enables comprehensive understanding of the effect of the condition itself and proper evaluation of treatment effectiveness beyond the objective clinical parameters.[4] The adult strabismus-20 (AS-20) questionnaire for QOL, developed by Hatt et al., has been used effectively in several previous strabismus studies.[2],[5],[6],[7],[8]In this study, we have evaluated the change in QOL of patients with poor BPS undergoing motor alignment using AS-20, particularly since no study has categorically used this instrument in cases with poor binocular potential.

  Materials and Methods Top

A tertiary care hospital-based prospective study was undertaken over a period of 1 year after approval from the local ethics committee. All patients of more than 10 years of age diagnosed with horizontal strabismus with Grade IV BPS [Annexure 1] were enrolled for the study. A detailed ocular examination and workup for strabismus was done. Angle of deviation was measured using prism alternate cover test. In cases where visual acuity did not allow accurate measurement with cover tests, Krismky's method was used. Strabismus correction was done using standard surgical recession and resection (unilateral) technique under general anesthesia. Successful surgical outcome was defined as either having a postoperative deviation of +10 prism Diopter (PD) of orthotropia or a correction of >50 PD in patients with deviation of >60 PD, latter being the maximum correction achievable by recession–resection surgery of one eye. However, patients who had outcomes outside the successful limits were excluded from the study. Patients with paralytic or restrictive strabismus and those having facial dysmorphism were also excluded.

The AS-20 questionnaire [Annexure 2] is a strabismus-specific questionnaire. It is a qualitative subjective patient-derived instrument devised by Sarah et al. in 2008 to calculate the health-related QOL in strabismus patients. It has 20 questions in two subscales: first, 10 questions assess psychosocial impact of the misaligned eyes, whereas the next 10 questions elicit the functional problems faced by the patients.

Patient response was recorded by marking the option that reflects the best how he/she feels after correction of his/her refractive error, if any, by glasses or contact lenses. It was completed unsupervised by the patient/parents in a clinical setting preoperatively and 3 months postoperatively. At both instances, the questionnaire was filled before any interaction with the patient in that visit.

AS-20 uses a five-point Likert scoring scale for each question: “never” (score 100), “rarely” (score 75), “sometimes” (score 50), “often” (score 25), and “always” (score 0). For ease of calculation, we have modified the scale as “never” (score 4), “rarely” (score 3), “sometimes” (score 2), “often” (score 1), and “always” (score 0) for ease of calculation. Thus, the maximum possible score was 40 (best QOL) and the minimum score was 0 (worst QOL) for each of the psychosocial and functional components. Binocular function was evaluated by WFDT and synoptophore responses (each ranging from 1 to 5) [Annexure 1]. Thus, best binocular functions were scored 10 and worst were scored 2.

Sample size was calculated for hypothesis testing about mean (two-tailed test) for both psychological and functional scores at alpha 5% and power 80% at 5% relative difference. The maximum sample size came out to be 49; however, all the available patients were taken into consideration and 53 study subjects were enrolled. The pre- and post-operative scores of overall AS-20, psychosocial subscale, functional subscale, and binocular functions were analyzed. Mean score to find the central tendency of each group was calculated. Comparison of preoperative psychosocial and functional scores was done using unpaired t-test. The preoperative mean scores were compared to the respective postoperative mean scores using paired t-test. Two-sided significance level (α =2 with confidence interval 95%), with P < 0.05 being considered statistically significant.

  Results Top

Among 53 patients, five patients were outside the limits of successful surgical outcome and hence were excluded from all statistical analysis. Out of the remaining 48 patients, 27 (56.2%) were females. The mean age of the patients at surgery was 20.4 ± 5.4 years (range: 11–37 years) with maximum patients in the age group of 21–30 years (47.16%). Esotropia was present in 18 patients with majority of cases of essential esotropia type and lateonset type (38% patients each), followed by sensory esotropia. Exotropia was seen in 30 patients with majority of cases (58%) of sensory type followed by basic type. The mean preoperative deviation was 29.1 ± 10.9 PD, whereas the mean postoperative deviation was 2.5 ± 3.0 PD. Statistically significant (P = 0.002) difference was seen between the psychosocial and functional scores preoperatively (19.7 ± 6.1; 23.1 ± 6.4, respectively). The improvement in mean psychosocial score was more than that for mean functional score. Mean preoperative AS-20 score was 21.5 ± 4.1 (20.4–22.7 with 95% confidence interval), whereas mean postoperative score was 32.4 ± 4.1 (31.2–33.5 with 95% confidence interval). Statistically significant improvement in postoperative mean overall AS-20, functional, and psychosocial scores (P = 0.001) was seen after successful surgery [Table 1]. There was no significant difference in change in QOL between males and females.
Table 1: Mean change in quality of life scores and binocular functions after successful ocular alignment (n=48)

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As expected, an insignificant difference was seen in the pre- and post-operative binocular functions [Table 1]. When the change in binocular function was correlated with the change in QOL, a correlation coefficient of 0.14 (P = 0.33) was noted. It was found that whatever minor change that was seen in binocular function could be correlated best (and significantly) to change in the functional subscores of AS-20 (correlation coefficient for change in psychosocial subscore was −0.11 with P = 0.41, whereas it was 0.31 for functional subscore with P = 0.02). It was further observed that only the patients with exotropia showed an improvement in binocular functions (change of 0.5 ± 1.5, with P = 0.2). In the exotropia group, an improvement in binocular function was noted only in the cases with freely alternating comitant exotropia. This was an expected finding, considering the normal progression history of this subtype of strabismus.[9]

On analysis of change in scores of each question, significant change (P < 0.02) was seen in 13 out of 20 questions (65%). The maximum change in points was seen in the sixth and tenth questions which deal with consciousness of self-appearance and the ability to initiate contact with strangers, respectively.

Mean preoperative ocular deviation was 28.1 ± 10.9 (range: 45 PD exotropia to 60 PD esotropia), whereas mean postoperative deviation was 5.2 PD (range: 5 PD exotropia to 8 PD esotropia). On comparing the change in QOL with the change in ocular deviation after surgery, a correlation coefficient of 0.10, 0.02, and 0.08 was seen for psychosocial, functional, and total scores, respectively, with insignificant P values (P = 0.47, 0.87, and 0.55, respectively).

  Discussion Top

A significant improvement in QOL can be experienced by the successfully aligned patients even in cases with poor binocular function. The presence of a significant difference between the change in psychosocial and functional scores implies that surgical ocular alignment brings about a much larger rehabilitation of the psychology of the patient as compared to improvement in sensory functions. Separate analysis of each question of the AS-20 further strengthened this observation. Thus, a maximal impact of surgical ocular alignment was noted in self-confidence and in the development of interpersonal relationships. Other submaximally affected questions address the issue of social perception of self-image.

A lower preoperative psychosocial score in our study demonstrates a more severe mental impact on patients as compared to the functional disability caused by the deviation. This may be attributed to the age of adolescence, by which most patients are expected to have adjusted to their functional problems but would have become more conscious of their appearance. Psychosocial subscale shows a larger change in health-related QOL probably because there is more scope for improvement in psychosocial score in patients with Grade IV BPS.[3] A significant improvement in functional subscale could be attributed to unexpected subjective sensory peripheral fusion after successful alignment.[10] Poor preoperative BPS in patients with alternate exotropia with good vision in both eyes is a result of prolonged alternate facultative suppression.[11] Such patients showed improvement from “alternate suppression” or “no binocular function” to binocular diplopia or “momentary fusion by kinetic stimulation,” respectively. Unexpected sensory fusion in this group may be attributed to comparable vision between the eyes of the patients with incomplete cortical suppression of fusion. This also explains better correlation of change in binocular function to change in functional QOL.

Previous studies listed out nonstrabismic factors such as depressive symptoms, type-D personality, and visually obstructive facial anomalies to lead to failures in the improvement of AS-20 scores.[12],[13] We achieved an improvement in QOL in spite of surgical failure as we excluded patients with facial anomalies. Patient perception of their condition may not relate to surgical outcomes[13],[14] as correction of the ocular deviation is only a surgeon's perspective. The patient may look at it with a different lens. The expectations of a patient from surgery may also reflect in their change in scores postoperatively, which may be unrelated to the actual surgical outcome.

There are multiple studies that report similar improvement in QOL as our study,[15],[16],[17],[18],[19],[20] but these studies enrolled patients that had variable binocular potential unlike our study where all seven criteria of having poor binocular potential were met.

This is the subset of patients where the benefits of doing the surgery are weighed against the costs[21] and the risks. Most often, only cosmetic benefits are taken into consideration. Although few studies[22],[23] have been done in the Indian subcontinent, none of them are specific to patients with poor binocular potential. Further, this study is one of the very few studies where the AS-20 has been used on the Indian population in cases with poor BPS, demonstrating the universal application of the questionnaire.

Further, unlike other studies,[6],[15],[23] we enrolled only those patients who needed unilateral horizontal recession resection surgery without any oblique muscle involvement as per- and post-operative experience may influence the overall mood and psychological benefits from squint correction. For the same reason, we used general anesthesia in all our cases in spite of doing unilateral surgery. A uniform per- and post-operative experience excludes out the confounding factor of pain-related variation of psychological response to surgical strabismus correction. We also excluded all those patients who had previously undergone corrective surgeries since their higher expectations from second surgery, desperation for correction, and perception of their condition could negatively affect their change in AS-20 scores.

However, more studies with longer follow-ups are required.

  Conclusion Top

To conclude, ocular alignment in patients with poor potential for binocular recovery is much more than mere “cosmetic” rehabilitation. It certainly and significantly improves QOL which consequently is a boost in personal, social, and professional aspects of life. In view of this, it may be proposed, after further detailed study, that insurance companies may consider reimbursement for strabismus surgery with poor binocular outcome, which for now is categorized under cosmetic procedures.[24],[25],[26]

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Conflicts of interest

There are no conflicts of interest.

  Annexures Top

  References Top

Crosby RD, Kolotkin RL, Williams GR. An integrated method to determine meaningful changes in health-related quality of life. J Clin Epidemiol 2004;57:1153-60.  Back to cited text no. 1
Hatt SR, Leske DA, Kirgis PA, Bradley EA, Holmes JM. The effects of strabismus on quality of life in adults. Am J Ophthalmol 2007;144:643-7.  Back to cited text no. 2
Singh V, Panday M, Agarwal S. Binocular potential score: A novel concept. J Pediatr Ophthalmol Strabismus 2008;45:104-8.  Back to cited text no. 3
Mills MD, Coats DK, Donahue SP, Wheeler DT; American Academy of Ophthalmology. Strabismus surgery for adults: A report by the American Academy of Ophthalmology. Ophthalmology 2004;111:1255-62.  Back to cited text no. 4
Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Development of a quality-of-life questionnaire for adults with strabismus. Ophthalmology 2009;116:139-44.e5.  Back to cited text no. 5
Hatt SR, Leske DA, Liebermann L, Holmes JM. Changes in health-related quality of life 1 year following strabismus surgery. Am J Ophthalmol 2007;153:614-9.  Back to cited text no. 6
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Hatt SR, Leske DA, Holmes JM. Responsiveness of health-related quality-of-life questionnaires in adults undergoing Strabismus surgery. Ophthalmology 2010;117:2322-8.e1.  Back to cited text no. 8
Yang CQ, Shen Y, Gu YS, Han W. Clinical investigation of surgery for intermittent exotropia. J Zhejiang Univ Sci B 2008;9:470-3.  Back to cited text no. 9
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Von Noorden GK, Campos EC. Principles of surgical treatment. In: Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed. St. Louis, MO: CV Mosby; 2001. p. 367-8.  Back to cited text no. 11
Hatt SR, Leske DA, Philbrick KL, Holmes JM. Factors associated with failure of adult strabismus-20 questionnaire scores to improve following strabismus surgery. JAMA Ophthalmol 2018;136:46-52  Back to cited text no. 12
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.McBain HB, MacKenzie KA, Hancox J, Ezra DG, Adams GG, Newman SP, et al. Does strabismus surgery improve quality and mood, and what factors influence this? Eye (Lond) 2016;30:656-67.  Back to cited text no. 14
Xu M, Yu H, Chen Y, Xu J, Zheng J, Yu X. Long-term quality of life in adult patients with strabismus after corrective surgery compared to the general population. PLoS One 2016;11:e0166418.  Back to cited text no. 15
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Ziaei H, Katibeh M, Mohammadi S, Mirzaei M, Moein HR, Kheiri B, et al. The impact of congenital strabismus surgery on quality of life in children. J Ophthalmic Vis Res 2016;11:188-92.  Back to cited text no. 17
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Liebermann L, Hatt SR, Leske DA, Holmes JM. Improvement in specific function-related quality-of-life concerns after strabismus surgery in nondiplopic adults. J AAPOS 2014;18:105-9.  Back to cited text no. 20
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